list_backends

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full burden of behavioral disclosure. It states that backends are not started, which implies a read-only intent, but does not mention potential side effects, output format, or error behavior. For a zero-parameter list operation this is adequate but not rich in context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Single sentence, front-loaded with the verb and object, and every word earns its place. No filler or redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple zero-parameter tool with no output schema, the description conveys the essential action and a key behavioral qualifier. It does not describe the return value (a list), but the tool's purpose implies it; given the low complexity, this is a near-complete definition.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

There are zero parameters, so schema coverage is vacuously 100%. The description adds no parameter-specific meaning, but none is needed since the tool takes no arguments. Baseline 3 applies per the rubric for high schema coverage.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb 'list' with a clear resource ('lazy MCP router runtime backends') and adds a qualifier ('without starting them') that distinguishes it from siblings like load_tool and call_tool. The purpose is unambiguous and immediate.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The phrase 'without starting them' provides clear context that this tool is for inspection only, implying alternatives exist for starting backends (e.g., load_tool). However, it does not name specific alternatives or provide explicit when-not conditions, so it stops short of a 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.